Actually Jason, I thought that it was a good clue (though I didn't get it).

The entrance to Robinson's Pot must be unique, inasmuch as it is in the yard outside a farmhouse, up against the kitchen wall, such that as you descend the short entrance pitch you actually go underneath the kitchen.

It's a privilege to be able to go down there, really – thanks to the family there for allowing access.

Apparently it's Robinsons' Pot (not "Robinson's"). This cropped up a while ago so I checked with one of the original 1975 (re)explorers and there was more than one Robinson.(Sorry for being what might be seen as unduly pedantic . . . )